Elevate Your .NET API Testing with Advanced Unit Testing Skills
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Chapter 1: Introduction to Advanced Unit Testing
Debugging can feel akin to being a detective in a mystery film, while ironically also being the culprit.” — Filipe Fortes
Unit tests are a familiar concept; they're essential, yet let's face it—they can sometimes be as thrilling as watching paint dry. But don’t worry, fellow developers! Crafting unit tests can be engaging and rewarding. In fact, they serve as the guardians of your code, protecting it from bugs and ensuring its long-term reliability.
In this guide, we will delve into advanced unit testing methodologies utilizing xUnit in .NET API development, particularly focusing on controllers, services, and repositories. We will also take you through a practical example of creating a Todo API from scratch, leveraging xUnit and Moq to develop thorough and effective unit tests. So, grab a cup of coffee, sit back, and prepare to elevate your unit testing skills!
Section 1.1: Project Setup
Before we plunge into advanced unit testing strategies, let’s set up our project. We will develop a basic Todo application featuring a controller, service, and repository. Follow these steps to establish your project:
- Launch Visual Studio 2022 and select “Create a new project.”
- Choose “ASP.NET Core API” and click “Continue.” Select .NET 6.0 as shown in the next image.
- Name your project “Todo” and click “Create.”
- Select “API” as the project template and click “Create.” Open the “TodoApi.csproj” file and include the following NuGet packages:
- “Microsoft.EntityFrameworkCore.InMemory” Version=”6.0.0-preview.7.21377.19"
- “Microsoft.NET.Test.Sdk” Version=”17.0.0"
- “Moq” Version=”4.16.1"
- “xunit” Version=”2.4.1"
- “xunit.runner.visualstudio” Version=”2.4.3"
Next, create a folder named “Models” and add a file called “TodoItem.cs” with the following code:
Following that, add a folder named “Data” and create a “TodoContext.cs” file containing the necessary code:
Next, create a “Repository” folder and include a “TodoRepository.cs” file, which also implements the ITodoRepository interface:
Now, add a folder called “Services” and generate a “TodoService.cs” file with the following code:
Then, create a controller under a folder named “Controllers” and name it “TodoController.cs”:
Chapter 2: Establishing the Test Project
To create a new test project in Visual Studio: Right-click on the solution in the Solution Explorer and select “Add” -> “New Project…” Under “Project types”, pick “Test” and under “Templates”, choose “xUnit Test Project.” Name your project “Todo.Test” and click “Create.”
After creating the test project, right-click on “Todo.Test” and add a reference to the “Todo” project.
Section 2.1: Testing the Controller
The controller acts as the gateway for our API, managing HTTP requests and generating HTTP responses. Using xUnit, we can assess the controller's performance across various scenarios. Here’s a sample test for when retrieving a todo item:
In this example, we instantiate the TodoController alongside a mock version of the ITodoService. We prepare the mock service to return a TodoItem when invoking the GetTodoItem method with an ID of 1. We then call the GetTodoItem method on the controller and verify that the result is an OkObjectResult containing the expected TodoItem.
We can also evaluate the controller's response when a requested item is absent:
Here, the mock service is set to return null when the GetTodoItem method is called with an ID of 1. We invoke the method on the controller and check that the result is a NotFoundResult.
Section 2.2: Testing the Service
The service layer interacts with the repository and applies business logic. Again, we utilize xUnit to scrutinize the service's behavior in different scenarios. Here’s a look at how to test the service when creating a new todo item:
Section 2.3: Testing the Repository
The repository is key for database interactions and CRUD operations. We can use xUnit to evaluate its behavior in various situations. For instance, here's how to test the repository when retrieving a todo item:
In this scenario, we create a new instance of the TodoRepository alongside an in-memory database context using Entity Framework Core. We construct a TodoItem and add it to the in-memory database. Calling the GetTodoItem method with the item's ID should return the created TodoItem.
Additionally, we can verify the repository's functionality when adding a new todo item:
In this test, we create a new TodoItem and invoke the AddTodoItem method on the repository, confirming the item was successfully added.
After running all tests, follow the provided steps to execute them successfully:
All tests executed successfully!
Conclusion
Congratulations! You've reached the end of this guide! Utilizing advanced unit testing methodologies such as xUnit and Moq can significantly enhance the quality and dependability of your .NET API applications. By following the examples outlined here, you can effectively test your controllers, services, and repositories to ensure they function correctly.
Incorporating unit testing into your development practices boosts the overall quality and maintainability of your code, leading to a better user experience for your application. So, don’t hesitate—start applying advanced unit testing techniques in your .NET API development today!
Check out the complete project on GitHub at the link below and customize it as needed!
Github Link
Within the project, you'll discover the complete code for the Todo API application, alongside additional resources and examples to help elevate your unit testing skills. Visit the project page now to start exploring!
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